HUNTSVILLE, Ala. (WHNT/CNN) -- Santa wasn't the only one racing against the clock to get packages to homes Tuesday night. UPS was too.
But the company's backlog left some Americans with gifts missing from under the Christmas tree Wednesday morning.
"We're terribly sorry," spokeswoman Natalie Black told CNN.
In a statement, the company explained that "the volume of air packages in our system exceeded the capacity of our network immediately preceding Christmas so some shipments were delayed."
"We know how hard it is for everyone to receive their holiday packages, and we're working around the clock to resolve this issue," Black said.
The Banks family in Huntsville raced to the front door everytime they heard a deliver truck pull into their neighborhood, but one special Christmas present didn't make it on time for present opening time.
"I'm just glad I had a backup plan," Sean Banks told WHNT News 19. "My wife would have been really mad if I had not scrambled to get something else wrapped up under the tree since her gift did not show up on time, even though it was supposed to be here on the 23rd," Banks added.
UPS stuck to its plan to make no deliveries on Christmas, angering some customers.
"Thanks for totally screwing us AND lying about it all day," Mo Husseini posted on Twitter. He was responding to a UPS tweet in which the company vowed "every effort to get packages to their destination."
"There will be an afternoon sort today," Black told CNN on Wednesday. "Workers will be processing packages so that tomorrow, bright and early, our drivers can clear out the remaining excess air volume. We expect that air volume to be delivered between tomorrow and Friday."
The company considered Christmas Day deliveries as an emergency measure, but "after much thought and consideration" decided not to ask drivers to work on the holiday. "They've pulled in extra hours. We did a lot of Sunday deliveries, which we normally don't do. It wasn't a decision that we came to lightly."
Asked why the company underestimated the volume of air packages it would receive, Black noted that previous severe weather in the Dallas area had already created a backlog. Then came "excess holiday volume" during a compressed time frame, since the period between Thanksgiving and Christmas was shorter than usual this year.
Add to that the consumer trend of doing more shopping online, she said.
"All of this culminated to become the perfect storm, so to speak."
Online retailers are damaged by UPS' mistake. These sites told customers their purchases would arrive in time for Christmas.
Some customers received messages from Amazon.com alerting them of the "failure in the UPS transportation network." In the message, the company offered to refund shipping charges and provide gift cards.
Amazon representatives could not be reached for comment immediately.
"We have a relationship with Amazon. We will definitely work with all of our retailers," Black said. "We're going to make good on our service commitments. What that exactly entails I don't know, but we'll work with them to maintain that relationship."
After January 2, the day the industry processes returns, the company will examine what happened and gauge its contingency planning and losses, she said.
Weather has caused delays in previous years. Technical glitches have as well, but Black said it's been "quite some time" since that happened.